classic waka stream

ふたり来し道とも見えぬ波のうへを
思ひかけでもかへすめるかな
Roma-ji

Futari koshi michi to mo mienu nami no ue o omoikakede mo kaesu meru kana

English Translation
Over these waters
where no trace shows of the road
the two of us came
I am being sent back now
as the waves come and go back
Meaning
Over these waters, where no trace shows of the road the two of us came by, I am being sent back — as the waves come and go back.
Commentary
141 The Road We Came By Together

A brother of the Consultant Yoshiie held a third-rank post in the province of Yamato. He brought a woman from Tsukushi and installed her in the house where his wife lived. The first wife was a kindly person and the new one bore her no ill will, and the two talked together on good terms. The man was often away on business in other provinces, so that the two women lived alone. The Tsukushi wife met another man in secret, and when someone taxed her with it she composed "Yowa ni idete tsuki dani mizu wa au koto o shirazugao ni mo iwamashi mono o". The first wife, being kind, said nothing to her husband; but he heard from elsewhere that she had taken up with a man, and though he turned it over in his mind he did not trouble himself much and let it be. When next they met he asked which of the two she cared for, himself or the other, and she answered with "Hanasusuki kimi ga kata ni zo nabiku meru omowanu yama no kaze wa fukedomo". Another man courted her too. She had been saying that love was nothing but grief and that she would have no more of men; but she was drawn to him by degrees, answered his letters, and at length sent a folded note to the first wife, which read: "Mi o ushi to omou kokoro no korineba ya hito o aware to omoisomuramu". That she could speak so openly, with no reserve at all, the first wife found endearing. But the Tsukushi wife, finding that the husband's feeling had changed and that he no longer loved her as before, said she would go home to her parents and brothers in Tsukushi; and he, being changed towards her, did not keep her. The first wife, used to her company, grieved at her going. They went together as far as Yamazaki to put her on the boat, and the husband came too. The second wife and the first talked together a day and a night, and in the morning she boarded. Husband and first wife got into the carriage to go home. Both parties felt it keenly; and from the boat came a letter: "Futari koshi michi to mo mienu nami no ue o omoikakede mo kaesu meru kana". Husband and wife both wept. The boat had put out, and no answer could be written. The carriage did not start but stood watching the boat go, and the woman aboard leaned out to look at the carriage, and as the boat was rowed away and the distance grew she went on gazing until the face was truly small — and the sorrow of it was very great. That is the whole of the section.
Yoshiie was a Consultant, and it is his brother who is the man here; he held the third rank in the provincial administration of Yamato. Of the first wife and the Tsukushi woman the prose tells us nothing further. Yamazaki, in Yamashiro province, was a chief point on the Yodo river route.
The setting is Yamazaki, with the Tsukushi woman aboard the boat and the husband and first wife in the carriage, about to go home.
What prompted the poem was that parting. It came from the boat as a letter.
Both wept, but the boat had put out and no answer could be written. The carriage stood watching, and the woman leaned out and gazed back until her face was truly small. On that the section ends.

The road the two of them came by is the road she once travelled up from Tsukushi with her husband.
Over water no track remains as it does on land, and the vanished road is stated as a plain fact of the scene.
The fourth line means without ever expecting it: she had not foreseen this.
The verb that closes means both that waves come and go back and that a person is sent back, and its form is that of something observed, so that she watches her own case from outside. The sea words hold throughout, and what the poem states is the desolation of retracing a road; the prose's account of the leave-taking carries the rest.
Source
Yamato Monogatari
Other